The new GOP majority in the U.S. Senate is turning up the heat on its investigation of allegations the Internal Revenue Service shared private taxpayer information with President Obama, demanding Obama turn over communications he and his staff had with the agency.

The Washington Times reported it obtained a copy of a letter signed by Senate Finance Committee Chairman Sen. Orrin Hatch, R-Utah, and the 13 other Republicans on the panel.

Addressed to Obama, the letter asks for his communications with the IRS since 2010 for their investigation into whether the agency has been engaging in illegal distribution of private taxpayer information. Republicans have accused the Obama administration of using the IRS as a political weapon since discovering the agency obstructed the applications for tax-exempt status of conservative organizations critical of Obama’s policies.

The letter said: “We have an obligation to conduct oversight of the federal government’s administration of our tax laws. As part of this oversight, we are seeking to determine the degree to and manner in which the Internal Revenue Service shares taxpayer information with the executive office of the president.”

IRS documents filed by the National Organization for Marriage, for example, were released to a citizen who asked for them, and they ended up in the hands of a homosexual activist who posted the confidential information online.

A judge ruled the IRS simply made a mistake, but the agency agreed to pay the group $50,000.

The documents requested by the Senate panel were also requested by the interest group Cause of Action, which has gone to court to try to compel the IRS inspector general to turn them over, the Times reported. The inspector general says it can’t turn over most of the 2,500 pages of records from its investigation because it would violate the privacy of taxpayers.